This invention relates to apparatus for optically recording the images of documents, in greatly reduced size, upon film while those documents are continuously being transported past an aperture area. Mirrors are used in the apparatus to keep it to a convenient size and shape as well as to allow both sides of the original documents to be recorded simultaneously.
A fast and automatic method of accomplishing such recording is made possible by the use of a flow, or rotary, type of recorder. The documents to be photographed are caused to enter a feed area by manual or automatic means, following which the apparatus moves them at essentially constant velocity through the photographic area and into a stacking hopper. As each document moves through the recorder, it trips a control switch which starts the film moving and opens the camera shutter. As the document passes through the aperture, or photographic area, the image of the document is reflected by a series of mirrors through the camera lens and onto the film which is moving at a speed proportional to the speed of the document. Since the movement of film and document is so proportioned, the image of the document is stationary, or essentially so, on the surface of the recording medium even though the image and film are both in motion.
It is often desirable to microfilm both sides of certain documents. For example, financial institutions such as banks desire to microfilm both sides of checks showing all endorsements, and find it convenient to have the front and back sides of each check adjacent each other for ease of retrieval and viewing. In order to accomplish this, the image of both sides of the document must be reflected by mirrors onto the microfilm adjacent each other. Furthermore, it is desirable to record at high document velocities since the volume of documents processed can be great.
Previously, rotary microfilm recorders used varying numbers of mirrors normally reflecting the image of the document in two or more planes. Two sided document recorders required more than two mirrors projecting the image in two or more planes. One example is the SRM Recorder manufactured by Bell & Howell Company which utilizes six mirrors projecting the document image in four planes. One reason for the use of mirrors is to cause the microfilm recorder to be compact and occupy a minimum amount of space. By folding the light path through the use of mirrors, the total length of the light path can exceed many times the length of the recorder itself.
It is desirable to utilize as few mirrors as possible, while conserving size and bulk, since each mirror requires time consuming and costly alignment and adjustment. One can appreciate that a slight misadjustment of any one mirror can move the document image out of alignment with the camera The greater the number of mirrors, the greater is the possibility of misalignment and the more difficult it becomes to properly realign the system. This results in increased manufacturing costs and service calls at the operating location. Also, the intensity of the document image is reduced somewhat each time it is reflected. This causes a need to use brighter, less economical lamps for document illumination, and increases the possibility of causing extraneous light to expose the film falsely.